Tailoring Structural, Microstructural, Dielectric and Gas Sensing Properties of SnO₂ Nanoparticles: Size Matters

This manuscript reports on the characteristics of SnO 2 nanoparticles (NPs) prepared using the conventional sol-gel technique and showcases the effect of calcination temperature on crystal structure, size, and gas-sensing properties. Rietveld refinement of diffraction profiles of SnO 2 NPs calcined at 400 °C [SnO 2 @400] and 600 °C [SnO 2 @600] showed that both the samples possess tetragonal phase having space group <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>P</mml:mi> <mml:msub> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>/</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:mspace width="0.25em"/> <mml:mi mathvariant="normal">mnm</mml:mi> </mml:math> . FESEM microimages of SnO 2 @400 and SnO 2 @600 were subjected to morphological analysis using an image processing method. The results showed that the grains exhibited swelling as the calcination temperature increased as per the Ostwald ripening process. High-resolution transmission electron microscopic (HRTEM) image depicted (110) lattice plane orientation with d = 0.34 nm consistent with XRD studies. Thus, the dielectric constant <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mfenced close=")" open="(" separators=""> <mml:mrow> <mml:mi>ε</mml:mi> <mml:mo accent="false">′</mml:mo> </mml:mrow> </mml:mfenced> </mml:math> was increased from 38 to 56 as the temperature rose to 600 °C from 400 °C. Simultaneously, electrical resistance increased from 0.77 × 10 6 Ω to 1.27 × 10 6 Ω with rise in the calcination temperature of SnO 2 NPs from 400 °C to 600 °C. The investigation on sensing acetone gas revealed that the SnO 2 @600 sample possessed the maximum sensing response along with a shorter recovery time compared with SnO 2 @400.